1. Field of the Invention
The present invention relates to a structure of a semiconductor light emitting element, particularly, an element structure having electrodes arranged on the opposite sides of a semiconductor and interposing the semiconductor.
2. Description of the Related Art
There is disclosed (for example, in Patent Document 1) a technology in which, in a light emitting element having a p-type semiconductor layer and a n-type semiconductor layer stacked interposing a light emitting layer, an electrode extending portion extending from a connection portion with an external electrode is formed along a periphery of an electrode forming surface for spreading electric current supplied to the both semiconductor layers on the entire surface of the semiconductor surfaces.
As one example, in a light emitting element 100 shown in a plane view in FIG. 14, a p-type electrode pad portion 102 connected with a p-type semiconductor layer is arranged in a center portion of the element. Also, an n-type electrode pad portion 101 connected to an n-type semiconductor layer is formed in a corner of a rectangular-shaped electrode forming surface. An electrode extending portion 101a extended from the n-type electrode pad portion 101 forms a surrounding electrode 101b completely surrounding all four sides of the electrode forming surface. The surrounding substrate 101b allows reducing the average distance that the electric current needed to travel laterally in the n-type semiconductor layer and, as a result, the series resistance of the device can be reduced and therefore, uniformity of the electric current density can be improved.
In recent years, to comply with demand of further high output, the area of the electrode structure at the n-electrode side has been increased, and accordingly, the surrounding electrode region has been increased, by disposing the surrounding electrode very closely to the edge of the element, in other words, by disposing the surrounding electrode without any space left between the surrounding electrode and the outer circumference of the element. In addition, a structure aiming to improve the uniformity of emission has been developed, in which the region surrounded by the electrode extending portion is further divided into a plurality of small regions by the electrode extending portion to uniformly spread the current in each region.
For example, in the light emitting element 200 shown in the plane view of FIG. 15, the electrode pad portion 201 is formed at a corner of the rectangular electrode forming surface. Further, the electrode extending portion 201a extended from the electrode pad portion 201 forms a surrounding electrode 201b encircling the circumference of the electrode forming surface. In addition, a plurality of the electrode extending portions 201a are evenly branched out from the orthogonally crossing two sides which form a corner portion of the electrode pad portion 201, and are respectively perpendicularly bent to divide the area within the surrounding electrode 201b into a plurality of compartments 203. In the example shown in FIG. 15, the plurality of compartment regions have a generally L-shaped configuration with different sizes which increase with the distance from the electrode pad portion 201, while the width of each of the regions is substantially the same. With this structure, the differences in local current density at the portions in the electrode forming surface can be reduced, that is, dispersion of the current is facilitated, so that the current density in the electrode forming surface is expected to be further uniform.    Patent Document 1: JP 2000-164930A